1. Field of the Invention
The present invention relates to a landing gear arrangement for a truck trailer of the type adapted to be removably connected with a tractor for transportation purposes. More particularly, the present invention relates to an improved, power driven landing gear system whereby the landing gear is operable by an electric motor that is controlled by a specially designed control system.
2. Description of the Related Art
Trailers of the type adapted for the transportation of goods are configured to be removably connectable with a tractor that includes the power plant for propelling the combined tractor and trailer. The tractor and trailer each include a component of a so-called fifth-wheel structure for effecting a secure connection between the tractor and the trailer. A trailer includes two or more pairs of rear wheels, and a landing gear toward the front end of the trailer. When the trailer is disconnected from the tractor, the forward end of the trailer, the end closest to the fifth-wheel connection, is supported by the landing gear legs, which can include at their lowermost ends either small wheels or pivotally supported pads. The landing gear legs are extendable and retractable, relative to the trailer frame, between an extended position and a retracted position. When the trailer is connected with a tractor the landing gear wheels are retracted, so that the front end of the trailer is supported by the tractor on the fifth wheel arrangement. And when the trailer is intended to be separated from the tractor the landing gear legs are extended to support the front end of the trailer to maintain the trailer bed in a substantially level position while the trailer is stationary and not connected with a tractor.
Most generally, the tractor landing gear is manually operated by means of a hand crank. The operator turns a crank in one direction or another either to extend the landing gear legs or to retract them, depending upon whether the trailer is connected with a tractor or not connected with a tractor. The hand crank operates through a reduction gear drive system to reduce the effort needed to cause the landing gear to extend or retract. However, despite the reduction gear drive, the effort required to extend the landing gear, in preparation for hook-up of the trailer with a tractor, is still a difficult task, particularly when the trailer is fully loaded with a heavy load. Thus, truck drivers and others who operate the trailer landing gear hand crank are sometimes injured as a result of the effort required to elevate a fully loaded trailer. Improper or careless cranking could result in back, arm, or hand injuries to the person operating the cranking mechanism.
In addition to the possibility of operator injury, improper positioning of the trailer front end during manual cranking of the landing gear extension and retraction system sometimes results in fifth-wheel damage. Generally, the tractor is connected with the trailer by backing the tractor toward the front end of the trailer to effect a connection by engaging the tractor portion and the trailer portion of the fifth wheel structure. Sometimes that connection attempt involves the application of ramming techniques whereby the tractor fifth wheel element is rammed into the trailer fifth wheel element during the tractor-to-trailer hook-up procedure. And if the trailer landing gear has not been manually extended a sufficient amount, to elevate the front of the trailer to a suitable elevation, ramming of the tractor to the trailer to connect the fifth-wheel arrangement could result in significant damage to the fifth-wheel system. Such improper positioning of the trailer sometimes results because of the difficulty involved in hand cranking a heavily loaded trailer to the correct hook-up height.
In addition to possible fifth-wheel damage, an improperly positioned trailer landing gear could also experience landing gear damage, sometimes called fold-out. Such damage can also occur because of the ramming technique used in the tractor-to-trailer hook-up procedure when the landing gear has not been properly extended to the correct position for permitting a smooth and clean hook-up. Many times when such fold-up occurs in the landing gear, both the trailer and the cargo it contains can sustain damage. Because of such trailer damage, it becomes necessary for the trailer to be taken out of service until a repair can be effected. Consequently, the trailer operator can experience operating losses because of such damage, in addition to possibly losing business because of too frequent incidents involving cargo damage. Accordingly, it is desirable to provide a power operated landing gear system to avoid the need for manual cranking, and to enable the landing gear to be easily positioned by a suitable motor. In that connection, the provision of pneumatic or electric motors to operate trailer landing gear systems has been suggested in the past. For example, a pneumatically-operated trailer landing gear arrangement is disclosed in U.S. Pat. No. 5,451,076, which issued on Sep. 19, 1995, to Paul Burkhead. That patent describes a pneumatic actuator for a trailer landing gear reduction assembly for raising or lowering of the landing gear of a trailer and to replace the hand crank. Additionally, in U.S. Pat. No. 4,466,637, which issued on Aug. 21, 1984, to Carl A. Nelson, there is disclosed a landing gear drive arrangement that includes an electric motor carried on the trailer frame and operable to power the landing gear between extended and retracted positions.
Although powered trailer landing gear arrangements have been disclosed in the past, they have not been widely adopted commercially. Additionally, the known powered landing gear drive arrangements are relatively unsophisticated and do not include safeguards to permit unauthorized operation of the landing gear drive system, which could make it easy for someone to steal a trailer along with its contents. Furthermore, the systems disclosed in the patents identified above, as well as in other patents, do not include sufficient control features to avoid damage to the drive system caused by incorrect operating procedures.
It is therefore an object of the present invention to overcome the deficiencies of the known powered landing gear drive systems and to provide an improved powered landing gear drive system that incorporates control functions to permit operation of the system only by authorized operators and to include built-in safeguards to prevent damage or injury to persons or property stemming from the operation of such systems.